1. Field of the Invention
The present invention relates to what is called a FIMS (Front-Opening Interface Mechanical Standard) system used to transfer wafers held inside conveyance containers called pods, between semiconductor processing apparatuses during semiconductor manufacturing processes. More specifically, the present invention relates to a substrate storage pod (pod) called a FOUP (Front-Opening Unified Pod), that is, a closed container used in the FIMS system and in which wafers are accommodated, as well as a lid opening/closing system that is a FIMS system configured to open and close a lid of the pod and to transfer the wafers to and from the pod.
2. Description of the Related Art
In recent years, in semiconductor manufacturing processes, only the inside of processing apparatuses, pods, and a mini-environment space through which substrates are delivered from the pods to the processing apparatuses are held in a high cleanliness state. The cleanliness of the other spaces is maintained at a certain level. The pod includes a shelf inside which a plurality of wafers can be held parallel to one another at intervals, a generally cubic-shaped pod case with an opening formed in one surface forming an outer surface thereof and though which the wafers are loaded and unloaded, and a lid configured to close the opening. Pods with the opening formed in one side surface (the surface located opposite a mini-environment space) of the pod instead of the bottom surface thereof are generally called FOUPs described above.
Furthermore, the above-described mini-environment space includes an opening portion located opposite the opening in the pod, a door configured to close the opening portion, another processing apparatus-side opening portion formed in a semiconductor processing apparatus side, and a transfer robot configured to enter the pod through the opening portion to hold a wafer and to covey the wafer to the processing apparatus side through the another processing apparatus-side opening portion. Additionally, a configuration forming the mini-environment space includes a mounting platform configured to support the pod so that the pod opening just faces to the front outer surface of the door. The mounting platform includes a positioning pin arranged on the upper surface thereof and fitted into a positioning slot formed in the lower surface of the pod to define a position where the pod is mounted, and a clamp unit also arranged on the upper surface of the mounting platform and engaged with a clamp portion provided on the pod lower surface to fix the pod to the mounting platform. The mounting platform can normally move a predetermined distance forward and backward with respect to the door. To allow a wafer in the pod to be transferred to the processing apparatus, first, the pod mounted on the mounting platform is moved until the lid of the pod comes into contact with the door. After the lid comes into contact with the door, the lid is removed from the pod opening portion by the door. These operations allow the inside of the pot to communicate with the inside of the processing apparatus via the mini-environment space. The operation of transferring a wafer is subsequently repeated. The mounting platform, the door, the opening portion, a door opening/closing mechanism, a wall in which the opening portion is formed and which forms a part of the mini-environment space, and the like as a whole are called a FIMS system described above.
For example, as disclosed in Japanese Patent Application Laid-Open No. 2001-077177, a conventional pod includes a fitting slot arranged in an inner surface of a pod case in the vicinity of an opening thereof, and a lid with a pawl that can be extended and retracted outward from the outer periphery of the lid. According to this scheme, the lid is fitted into the pod case by insertion in a predetermined manner, and the pawl of the lid is extended. The extended pawl is inserted into the fitting slot in the pod case to fix the lid to the pod case. Furthermore, the above-described operation is reversely performed to unfix the lid from the pod case. The pawl is generally extended and retracted by fitting what is called a key member, from the outside of the lid surface, into an operating portion connected to the pawl and arranged at a predetermined position in a central area of the lid, and then operating the key member. The contact and pivoting of the above-described member, the resultant sliding and the like normally result in dusting, which may affect semiconductor manufacturing and which thus needs to be acknowledged as a problem. However, the dust is migrated to the mini-environment space in which a down flow is formed before the dust diffuses through the micro gap between the surface of the lid and the surface of the door to the outside of the gap. Thus, the diffusion of the dust into the mini-environment space or the pod is not so serious as to be acknowledged as a problem. Hence, no specific action has been taken on the dust. Furthermore, the pod is normally conveyed in a space with a lower cleanliness. Thus, dust may be attached, in the space, to the outer peripheral surface of the pod main body and the surface of the lid, or for example, hydrocarbon contained in the air may be stuck thereto. The suppressive effect based on the down flow is expected to work suitably on this problem as well as on the dust resulting from the operation of the above-described key member or the like.
For semiconductor devices, progressive effort has been made to enhance the functions of elements and to miniaturize the elements. Thus, a wiring width, design rules and the like used for the elements have been reduced. As a result, the presence of the smaller dust, which conventionally poses no problem, needs to be noted. Such micro dust, unlike the dust against which measures are conventionally taken, migrates through the space based on an operation different from the conventional one, such as what is called Brownian motion or the effect of micro static electricity. Specifically, even with an attempt to allow the above-described down flow to sweep such micro dust away to below the mini-environment space and to further discharge the micro dust to an external space, the micro dust is not simply swept away by a gas flow but may float into the mini-environment space. Japanese Patent No. 3417821 discloses a configuration including a pivoting lever arranged outside the pod-side opening instead of the pawl arranged on the lid so that with the opening closed by the lid, the lever presses and holds the lid from the lid surface side. In this configuration, generation of dust resulting from the operation of the key member as described in Japanese Patent Application Laid-Open No. 2001-077177 occurs around the periphery of the opening. Thus, the level of diffusion of the dust from the lid and from the door holding the lid may be reduced compared to that in the configuration disclosed in Japanese Patent Application Laid-Open No. 2001-077177. However, the lever needs to be operated before the lid is opened or closed, and a configuration for this operation is present around the periphery of the opening portion. Hence, the micro dust present in the external space may diffuse toward the mini-environment space.
Furthermore, a recent increase in the diameter of wafers has led to an increase in the size of pods in which wafers are accommodated. In such a large-sized pod, when the lid of the pod is closed, the door configured to hold the lid performs a significant amount of operation, and a strong driving force needs to be exerted for the closure. Thus, in the conventional relationship between the door and the pod lid, it is expected to be difficult to suitably fix the pod lid to the pod simply by operating the door. Hence, the need arises to suppress the adverse effect of micro dust stuck to the surface of the lid configured to close the pod opening and to restrain generation of dust resulting from an opening or closing operation performed when the lid is opened or closed as well as diffusion of the generated dust into the mini-environment space or the inside of the pod.